Synthesis of a Novel Interconnected 3D Pore Network Algal Biochar Constituting Iron Nanoparticles Derived from a Harmful Marine Biomass as High-Performance Asymmetric Supercapacitor Electrodes

Abstract

Via the activation treatment on Cladophora glomerata (CG) with FeCl 3 and KOH, magnetic biochar (MBC) with olive-shaped pores and functional biochar (FBC) with a novel interconnected 3D pore network structure have been successfully prepared by a facile slow pyrolysis process to be applied as electrodes in supercapacitors. To obtain Fe composite biochar (FCBC), FBC was functionalized with HNO 3 and H 2 SO 4 for extending formation of iron oxide through the hydrothermal method. These electrodes demonstrate remarkable electrochemical behaviors, in terms of wonderful rate capability, high specific capacitance and excellent cycle stability when first served as electrodes for supercapacitors. In addition, we have successfully fabricated an asymmetric supercapacitor with high energy and power densities using FBC as the anode electrode and iron oxide/ carbon composites (MBC and FCBC) as the cathode electrodes in a neutral aqueous 3 M KCl electrolyte. Because of the desirable porous structure, high specific capacitance, rate capability, and complementary potential window of the two electrodes, the asymmetric supercapacitor can be cycled reversibly in a wide potential window of 0−1.8 V and exhibits energy density 41.5 Wh kg −1 at a power density of 900 W kg −1 for FBC//FCBC. The asymmetric supercapacitor also presents stable cycling performance with 93.1% for FBC//FCBC capacitance retention at 8 A g −1 after 10000 cycles. These encouraging results show great potential in developing energy storage devices with high energy and power densities for practical applications.

Biomass‐Derived Carbon: A Value‐Added Journey Towards Constructing High‐Energy Supercapacitors in an Asymmetric Fashion

“…Ac omparison of the Ragoneplots obtained for ASCs constructedf rom BDC materials reported herein. CNB/MnO 2 @CNB (BDC = tofu), [128] AMC/ZnCO (BDC = almond shells), [122] EDAC/MnS (BDC = eggplant), [145] NPC/PC@MnO 2 (BDC = loofah sponge), [130] NKGLC/Ni(OH) 2 -MnO 2 -rGO (BDC = ginkgo leaf), [158] PC/NiCo 2 S 4 @PC (BDC = popcorn pieces), [156] APC/NiCo 2 O 4 (BDC = walnut shells), [151] HC/MnO 2 @HC (BDC = hemps tems), [126] PFN/PFNC (BDC = pomelo fruit), [150] BioHPC/NiCo 2 O 4 -NS (BDC = corncob), [152] N-CBC/CBC-N@LDH (BDC = bacterial cellulose pellicles), [133] p-BC-N/MnO 2 @p-BC (BDC = bacterialcellulose pellicles), [87] HSC/Ni-Co-Al LDH (BDC = bacterial cellulose pellicles), [134] CCNS/ MnO 2 @CCNS (BDC = willowc atkin) [57] PCMT/b-Ni(OH) 2 @ACMT (BDC = willow catkin), [89] FBC/FCBC (BDC = CG), [154] Fe 2 O 3 @BPC/CNT@CoNiLDH( BDC = wheat straw), [157] GPCN-SS/ MnO 2 @GPCN-SS( BDC = SS), [135] and MnSi-C/Ni(OH) 2 (BDC = bambool eaves). [147] Figure 15.…”

“…[154] CG wass tirred in a solution of FeCl 3 and the dried material was then pyrolyzed at 700 8Cf or 4hunder an argon atmosphere to give magnetic biochar (MBC). [154] CG wass tirred in a solution of FeCl 3 and the dried material was then pyrolyzed at 700 8Cf or 4hunder an argon atmosphere to give magnetic biochar (MBC).…”

“…Pourhosseini et al developed an ovel interconnected 3D porousn etwork containing iron nanoparticles from harmful marine biomass, Cladophora glomerate (CG), whichw as utilized as an electrode materiali nA SCs. [154] CG wass tirred in a solution of FeCl 3 and the dried material was then pyrolyzed at 700 8Cf or 4hunder an argon atmosphere to give magnetic biochar (MBC). Furthermore, functional biochar (FBC) wasp repared by mixingd ried microalgae with 6 m KOH or refluxing H 2 SO 4 and HNO 3 at 80 8Cf or 6h.T he resulting suspensions were pyrolyzed at 700 8Cf or 2h to create a3 Dp ore network structure.…”

Partially Graphitized Iron−Carbon Hybrid Composite as an Electrochemical Supercapacitor Material

“…The SSA of CF20 is ∼190 m 2 g −1 which is lesser than CF0 and CF10 (Figure S3b). The decrease in CF20 SSA might be due to the higher loading of iron oxide which occupied the void and surface space in the layered material …”

Partially Graphitized Iron-Carbon Hybrid Composite as Electrochemical Supercapacitor Material

“…The drastically decrease in CF20 SSA might be due to higher loading of iron oxide which occupied the void space in the layered material. [33][34] CF0 and CF20 as compared to CF10 as Csp is directly related to the area under the CV curve. On the basis of above discussion, it could be concluded that CF10 has the best capacitive performance.…”